Rust-inhibited silicate base oils



'firearms on airplanes. .leave the Warm air of the earths surface at a very high rate of speed and attain high altitude rapidly. As a re atent United States RUST-INHIBITED SILICATE BASE OILS Robert L. Peeler, Jr., Richmond, and Edward G. Foehr, San Rafael, Califi, assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Application February 9, 1953, Serial No. 335,986

Claims. (Cl. 252---33.4)

This invention pertains to a machine gun lubricant comprising a major proportion of a silicate base oil (e. g., tetraalkyl silicate) and minor proportions of polyvalent metal sulfonates and polyglycol ethers, that ,is, alkylpolyalkyleneglycol ethers.

The lubricant set forth herein inhibits the formation of rust on machine guns, more especially so for guns mounted on airplanes. It is imperative that all firearms are well protected from rust in order that they may always be available for instant use.

Ideal rust conditions are inherent in the operation of For example, jet fighter planes .sult, the guns and their-firing mechanisms become exceedingly cold. When these planes drop to lower altitudes for purposes of strafing or for purposes of unloading rockets or bombs, moisture condenses on the cold metal. When the planes again rise rapidly into the atmosphere, the guns again become cold. These alternate freezing-sweating cycles are conditions which are ideal for the formation of rust on and in the guns.

The lubricating oil compositions herein not only prevent rust formation on and in the firearms, but they also lubricate the recoil mechanisms and other component parts of firearms at extremes of temperatures encountered during such service as exemplified hereinabove.

Heretofore, mineral oils and synthetic diester oils have been used as the base oils in machine gun lubricating compositions. However, both of these base oils have numerous disadvantages. Mineral oils are quite easily sweated and evaporated oif of the guns during this alternate freezing-sweating cycle, the mineral oil composition being removed by the action of ice and water droplets and by evaporation. Thus, the loss of the mineral oil composition results in rust formation. Furthermore, mineral oils which are effective at atmospheric temperatures become too viscous for satisfactory operation of the gun equipment at the lower temperatures encountered at higher altitudes. The firing mechanism becomes too sluggish, and the time of response to the trigger action is considerably increased.

A disadvantage in the use of diester synthetic lubn'cating oils is that rust-inhibitors are not as effective in diester synthetic lubricating oils as compared to the base oils of the composition of the present invention. Furthermore, diester synthetic base oils cause rubber to swell, the rubber gradually deteriorating and losing its original form and resiliency. Diester synthetic lubricating oils also attack paint compositions, dissolving the paint com-, positions from the metal. I

The machine gun lubricant of this invention does not have the disadvantages noted hereinabove for the mineral and diester baseoils. The compositions set forth herein do not attack paint, do not cause rubber to swell or deteriorate, do not become too viscous at low temperanot removed from gun equipment by alternate sweatingfreezing action, etc. Disadvantages of former machine gun lubricants are rectified by the composition set forth in this invention.

According to the present invention, it has been discovered that a rust-inhibited machine gun lubricant is obtained by blending together a silicate base oil, a metal sulfonate, and an alkylpolyalkylene'glycol ether.

The machine gun lubricant of this invention comprises a major proportion of a silicate base oil and minor amounts each of a metal sulfonate and a polyglycol ether.

The silicate base oils used herein are represented by the following formula:

wherein the Rs are branched-chain or straight-chain alkyl radicals having from 4 to 18 carbon atoms; that is, the Rs can have a total of from 16 to 72 carbon atoms. The Rs in the silicate base oil may be similar or dissimilar; that is, one R may represent an alkyl radical having 4 carbon atoms, and the other Rs may represent alkyl groups having 12 carbon atoms; on the other hand, all of the Rs may be aliphatic radicals each having 8 carbon atoms. It is readily understood that in the formation of the silicates used herein as base oils, that a ran dom distribution exists among the Rs. Whereas, it may be desired that the Rs are dissimilar, a minor percentage of the silicates in the base oil may contain aliphatic radicals which are all alike.

It is preferred that the Rs be radicals derived from branched-chain primary alcohols having from 6 to 8 car-. bon atoms, and that the silicates have molecular weights of at least 350. It is especially preferred that the Rs in the above formula represent the Z-ethylhexyl radical and/or the 2-ethyl-1-butyl radical. The silicates useful as base oils according to this invention are liquid at room temperature.

Examples of silicate base oils of this invention include the following: tetrabutyl silicate, tetraamyl silicate, tetra.- hexyl silicate, tetra (Z-ethylhexyl) silicate; tetra (2-ethyll-butyl) silicate; dibutyl, di (Z-ethylhexyl) silicate; tetra.- octyl silicate; dibutyl, dioctadecyl silicate; tetradodecyl silicate; tetrahexadecyl silicate, etc. i

In addition to the silicates of the formula above, the

also include those silicates of the formula:

bination of this invention for the silicate base oils set forth hereinabove are polyvalent metal sulfonates represented by the formula:

equalto the valence of the metal M.

tures for maximum speed of firing of gun equipment, are

As the metal, the metals of Groups I and II of Mendeleetfs Periodic Table and lead can be used; of these, however, sodium, potassium, calcium, barium, strontium, zinc and lead are preferred.

,It is desirablethat the metal ,sulfona tes be oil-soluble.

By essentially hydrocarbonaceous radical is meant those radicals which are composed mainly of hydrogen and carbon, and include such radicals which contain, in addition, minor amounts of substituents such as chlorine, bromine, oxygen, hydroxyl groups, etc., which do not substantially affect their hydrocarbon character.

Examples of suitable hydrocarbonaceous radicals are the following: dodecyl, hexadecyl, eicosyl, triacontyl, hexadecyl phenyl, octadecyl phenyl, hexadecyl naphthyl radicals; radicals derived from petroleum hydrocarbons such as white oil, wax, olefine polymers (e. g., polypropylene and polybutylene, etc.), etc. The sulfonic acids used in preparing the sulfonates of this invention also include the oil-soluble sulfonic acid obtained from petroleum, such as the mahogany acids and the synthetic sulfonic acids prepared by various methods of synthesis (e. g., sulfonic acids prepared by reacting a chorinated white oil with benzene, using hydrofluoric acid as the catalyst, then treating the resulting white oil alkylated benzene with chlorosulfonic acid or fuming sulfuric acid to form a white oil benzene sulfonic acid).

The metal sulfonates are exemplified as follows: sodium white oil benzene sulfonate, calcium white oil benzene sulfonate, lead, white oil benzene sulfonate, calcium dipolypropene benzene sulfonate, zinc dipolypropene benzene sulfonate, barium dipolypropene benzene sulfonate, calcium mahogany petroleum sulfonate, sodium mahogany petroleum sulfonate, barium mahogany petroleum sulfonate, strontium mahogany petroleum sulfonate, calcium triacontyl sulfonate, zinc triacontyl sulfonate, calcium dodecane sulfonate, lead dodecane sulfonate, etc.

The alkyl polyalkyleneglycol ethers used herein in combination with sulfonates have terminal groups which contain a total of no more than 30 carbon atoms, any one terminal group containing no more than 20 carbon atoms; and have no more than 18 polyalkylene glycol units, each unit containing no more than 4 carbon atoms.

The'alkylpolyalkyleneglycol ethers are represented by the formula:

wherein R is a divalent straight-chained or branch-chained saturated hydrocarbon radical containing from 2 to 4 carbon atoms, preferably 2 carbon atoms; R1 is an alkyl radical containing from 1 to 20 carbon atoms; R2 is hydrogen, an acyl radical containing from 1 to 20 carbon atoms, or an alkyl radical containing from 1 to 20 carbon atoms; and n is a number having a value from 2 to 18, preferably from 2 to 8. It is preferred that R1 and R2 are alkyl radicals, each containing from 3 to 8 carbon atoms. R1 and R2 may be similar or dissimilar.

Examples of R radicals include the divalent radicals: ethylene, propylene and butylene.

Examples of R1 and R2 radicals include radicals derived from methane, ethane, propane, isopropane, butane, isobutane, tert.-butane, pentane, isopentane, neopentane, hexane, isohexane, octane, 2-ethyl heptane, dodecane, tetradecane, hexadecane, octadecane, eicosane, docosane, tetracosane, etc.

In the combination with the polyglycol ethers set forth herein, the metal sulfonates are used in amounts of 0.01% to 20%, by weight. However, it is preferred to use amounts of 0.1% to The polyglycol ethers of this invention are used in amounts of 0.01% to by weight of finished composition; preferably 0.1% to 3%.

For the purpose of this invention, certain ratios of polyglycol ethers to metal sulfonates are particularly beneficial. Although the ratios of polyglycol ethers to sulfonates in silicate oils may have values ranging from 0.2 to 10.0, it is especially preferred that the ratios of polyglycol ethers to sulfonates have values ranging from 0.5 to 2, by weight.

In determining the effectiveness of the combination of metal'sulfonates and polyglycol ethers as rust inhibitors 4- in silicate base oils, the oils to be tested were coated on steel panels and the coated steel panels were subjected to a high humidity cabinet test which was run as follows:

Steel panels having the dimensions of 2 in. x 3 in. x in. with well rounded edges were sandblasted to a fresh, uniformly abrasive surface. These panels were then totally immersed in the test oil for one minute, suspended for two hours to permit free drainage of the excess oil therefrom, then placed in a cabinet having a humidity of at F. When a speck of rust was noted in an area at least Vs in. from the border of the steel panel, the time was noted as the hours to first rust. When more than two specksof rust appeared in; an area more than A; in. from the border of the steel panel, the time noted was the hours to failure.

The silicate base oils per se, when placed in the humidity cabinet, failed almost immediately, that is, within the first observance time, which in all instances was two hours. The addition of polyglycol ethers to the silicate oils did not affect the time to failure. The test panels still failed within the first two-hour observance time.

The tables set forth hereinbelow present test data obtained in the humidity cabinet test. All of the data in Table I were obtained with a base oil consisting of tetraamyl silicate.

Table I Polyglycol Ratio of Hours Test N O g gzgf' Ether, Polyglycol to Hour b Wt Percent Ether to First F P y by Wt. Sulfonate Rust we 1-- l 2 2 l 2 3. 0 (ll) 96 2. 5 (b) 96 1. 5 (C) 96 2 0 (C) 144 1. 0 (d) 4 (ti) 4 144 1. 0 (C) 10 (d) 10 144 2. 0 (C) 1 (d) 0. 5 200+ 2. 0 (C) 2 (d) 1. 0 200+ 200+ 3. 0 (C) 2 (d) 0. 67 200+ 200+ 2. 0 (C) 2 (6) 1. 0 209+ 209+ 2. 0 (c) 2 (f) 1. 0 214+ 214+ T38 first observance of the test panels was made at the two-hour perro (a) A calcium petroleum sulfonate having a molecular weight of about 425.

(b) A barium petroleum sulionate.

(c) A calcium alkyl benzene sultonate having a molecular weight of approximately 1100.

Table II Polyglycol Ratio of sulfonate, Ether P01 1 01 Hours to H Test N0 ggy by Percent by El lil t o g F iiil iirie Wt. Sulionate us The silicate base oil containing the sulfonate-polyglycol ether combination of this invention can be used as an internal combustion engine lubricating oil. When grease thickening agents are incorporated therein to thicken the composition to the consistency of a grease, the rust-inhibited composition may be used for bearings, gear assemblies, etc. Such oils and-greases prevent attack by moisture or other corrosive agents to aluminum brass, bronze, hard metal alloys such as copper-lead, cadmiumsilver, etc.

In addition to the compositions noted hereinabove, the silicate base oils may contain other rust-inhibiting compounds, extreme pressure additives, color correctors, oxidation inhibitors, fattiness agents, etc.

We claim:

1. A machine gun lubricant comprising a major proportion of a silicate oil, from about 1 to about 3% by weight of a metal sulfonate, the metal being selected from the group consisting of lead and the metals of Group I and II of Mendeleefis Periodic Table, and from about 1 to about by weight of an alkyl polyalkylene glycol ether having the formula wherein R is a divalent hydrocarbon radical containing from 2 to 4 carbon atoms, R1 and R2 are hydrocarbon groups each having not more than 20 carbon atoms and together having not more than 30 carbon atoms and n is a number from 2 to 18, the weight ratio between the ether and sulfonate being from about 0.2 to about 10.

2. A machine gun lubricant comprising a major proportion of a tetraalkyl silicate oil wherein each alkyl group contains from 4 to 18 carbon atoms, from about 1 to about 3% by weight of a metal sulfonate, the metal being selected from the group consisting of lead and the metals of Groups I and II of Mendeleefis Periodic Table, and from about 1 to about 10% by weight of an alkyl polyalkylene glycol ether having the formula wherein R is a divalent hydrocarbon radical containing from 2 to 4 carbon atoms, R1 is an alkyl radical containing from 1 to 20 carbon atoms and n is a number from 2 to 18, the weight ratio between the ether and sulfonate being from about 0.2 to about 10.

3. A machine gun lubricant comprising a major proportion of a tetraalkyl silicate oil wherein each alkyl group contains from 4 to 18 carbon atoms, from about 1 to about 3% by weight of a metal sulfonate, the metal being selected from the group consisting of lead and the metals of Groups I and II of Mendeleeffs Periodic Table, and from about 1 to about 10% by weight of an alkyl polyalkylene glycol ether having the formula wherein R is a divalent hydrocarbon radical containing from 2 to 4 carbon atoms, R1 and R2 are hydrocarbon groups each having not more than 20 carbon atoms and together having not more than 30 carbon atoms and n is a number from 2 to 18, the weight ratio between the ether and sulfonate being from about 0.5 to about 2.0.

4. A machine gun lubricant comprising a tetraalkyl silicate oil wherein each alkyl group contains from 6 to 8 carbon atoms, from about 1 to about 3% of an alkaline earth metal sulfonate and from about 1 to about 10% by weight of an alkyl polyalkylene glycol ether having the formula wherein R is a divalent radical selected from the group of ethylene and propylene, R1 and R2 are alkyl radicals each containing from 3 to 8 carbon atoms, and n is a number from 2 to 8, the weight ratio between the ether and sulfonate being from about 0.5 to about 2.0.

5. A machine gun lubricant comprising a major proportion of a tetraalkyl silicate oil wherein each alkyl group contains from 4 to 18 carbon atoms, from about 1 to about 3% by weight of an alkaline earth metal petroleum sulfonate, and from about 1 to about 10% by weight of an alkyl polyalkylene glycol ether having the formula wherein R is a divalent radical selected from the group of ethylene and propylene, R1 and R2 are alkyl radicals each containing from 3 to 8 carbon atoms and n is a number from 2 to 8, the weight ratio between the ether and sulfonate being from about 0.5 to about 2.0.

6. A machine gun lubricant comprising a major proportion of a tetraalkyl silicate oil wherein each alkyl group contains 6 to 8 carbon atoms, from about 1 to 3% by weight of a calcium alkyl benzene sulfonate, from about 1 to 3% by weight of an alkyl polyalkylene glycol ether of the formula wherein R is a divalent radical selected from the group of ethylene and propylene, R1 and R2 are alkyl radicals each containing from 3 to 8 carbon atoms, and :1. is a number from 2 to 8, the Weight ratio between the ether and sulfonate being from about 0.5 to about 2.0.

7. A machine gun lubricant comprising a major proportion of a tetraalkyl silicate oil wherein the alkyl groups are derived from branched chain rimary alcohols having from 6 to 8 carbon atoms, from about 1 to about 3% by weight of an alkaline earth metal petroleum sulfonate, from about 1 to about 10% by weight of an alkyl polyethylene glycol acetate wherein the alkyl radical contains from 3 to 8 carbon atoms, and wherein 2 to 8 ethylene groups are present, the weight ratio between the ether and sulfonate being from about 0.2 to about 10.

8. A machine gun lubricant comprising a major proportion of a tetraamyl silicate, from about 1 to about 3% by weight of a calcium alkyl benzene sulfonate, from about 1 to about 10% of a polypropylene oxide methyl butyl diether containing an average of eight polypropylene oxide units, the weight ratio between the ether and sulfonate being from about 0.2 to about 10.

9. A machine gun lubricant comprising a major proportion of a tetra (Z-ethylhexyl) silicate, from about 1 to about 3% by weight of a calcium alkyl benzene sulfonate, from about 1 to about 10% of a polypropylene oxide methyl butyl diether containing an average of eight polypropylene oxide units, the weight ratio between the ether and sulfonate being from about 0.2 to about 10.

10. A machine gun lubricant comprising a major proportion of a silicate oil, from about 1 to about 3% by weight of a metal sulfonate, the metal being selected from the group consisting of lead and the metals of Groups I and II of Mendeleefts Periodic Table, and from about 1 to about 10% by weight of an alkyl polyalkylene glycol ether having the formula 0 CH3-&-O(R-O-)MR1 wherein R is a divalent hydrocarbon radical containing from 2 to 4 carbon atoms, R1 is an alkyl radical containing from 3 to 8 carbon atoms, and n is a number having a value from 2 to 8, the weight ratio between the ether and sulfonate being from about 0.2 to about 10.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A MACHINE GUN LUBRICANT COMPRISING A MAJOR PROPORTION OF A SILICATE OIL, FROM ABOUT 1 TO ABOUT 3% BY WEITHT OF A METAL SULFONATE, THE METAL BEING SELECTED FROM THE GROUP CONSISTING OF LEAD AND THE METALS OF GROUP I AND II OF MENDELEEFF''S PERIODIC TABLE, AND FROM ABOUT 1 TO ABOUT 10% BY WEIGHT OF AN ALKYL POLYALKYLENE GLYCOL ETHER HAVING TH FORMULA 